This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present techniques. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present techniques. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
The production of hydrocarbons, such as oil and gas, has been performed for numerous years. To produce these hydrocarbons, a production system may utilize various devices, such as sand screens and other tools, for specific tasks within a well. Typically, these devices are placed into a wellbore completed in either a cased-hole or open-hole completion. In cased-hole completions, a casing string is placed in the wellbore and perforations are made through the casing string into subterranean formations to provide a flow path for formation fluids, such as hydrocarbons, into the wellbore. Alternatively, in open-hole completions, a production string is positioned inside the wellbore without a casing string. The formation fluids flow through the annulus between the subsurface formation and the production string to enter the production string.
However, when producing hydrocarbons from subterranean formations, operations become more challenging because of the location of certain subterranean formations. For example, some subterranean formations are located in intervals with high sand content in ultra-deep water, at depths that extend the reach of drilling operations, in high pressure/temperature reservoirs, in long intervals, at high production rate, and at remote locations. As such, the location of the subterranean formation may present problems, such as loss of sand control, that increase the individual well cost dramatically. That is, the cost of accessing the subterranean formation may result in fewer wells being completed for an economical field development. For example, loss of sand control may result in sand production at the surface, downhole equipment damage, reduced well productivity and/or loss of the well. Accordingly, well reliability and longevity become design considerations to avoid undesired production loss and expensive intervention or workovers for these wells.
Sand control devices are an example of a device used in wells to increase well reliability and longevity. Sand control devices are usually installed downhole across formations to retain solid material and allow formation fluids to be produced without the solid materials above a certain size. Typically, sand control devices are utilized within a well to manage the production of solid material, such as sand. The sand control device may have slotted openings or may be wrapped by a screen. As an example, when producing formation fluids from subterranean formations located in deep water, it is possible to produce solid material along with the formation fluids because the formations are poorly consolidated or the formations are weakened by downhole stress due to wellbore excavation and formation fluid withdrawal.
However, under the increasingly harsh environments, sand control devices are more susceptible to damage due to high stress, erosion, plugging, compaction/subsidence, etc. As a result, sand control devices are generally utilized with other methods, such as gravel packing or fluid treatments to manage the production of sand from the subterranean formation.
One of the most commonly used methods to control sand is a gravel pack. Gravel packing a well involves placing gravel or other particulate matter around a sand control device coupled to the production string to enhance sand filtration and formation integrity. For instance, in an open-hole completion, a gravel pack is typically positioned between the wall of the wellbore and a sand screen that surrounds a perforated base pipe. Alternatively, in a cased-hole completion, a gravel pack is positioned between a casing string having perforations and a sand screen that surrounds a perforated base pipe. Regardless of the completion type, formation fluids flow from the subterranean formation into the production string through at least two filter mechanisms: the gravel pack and the sand control device.
With gravel packs, inadvertent loss of a carrier fluid may form sand bridges within the interval being gravel packed. For example, in a thick or inclined production intervals, a poor distribution of gravel (i.e. incomplete packing of the interval resulting in voids in the gravel pack) may occur with a premature loss of liquid from the gravel slurry into the formation. This fluid loss may cause sand bridges that form in the annulus before the gravel pack has been completed. To address this problem, alternate flowpaths, such as shunt tubes, may be utilized to bypass sand bridges and distribute the gravel evenly through the intervals. For further details of such alternate flowpaths, see U.S. Pat. Nos. 5,515,915; 5,868,200; 5,890,533; 6,059,032; 6,588,506; 4,945,991; 5,082,052; 5,113,935; 5,333,688 and International Application Publication No. WO 2004/094784; which are incorporated herein by reference.
Utilizing alternate flow paths is highly beneficial, but creates design challenges in making up a production string, such as coupling a packer to a sand control device or other well tools. The packer prevents flow through the wellbore around the alternate flow path, while permitting flow within the alternate flow path and in many instances through a primary flow path in addition.
While the shunt tubes assist in forming the gravel pack, the use of shunt tubes may limit methods of providing zonal isolation with a gravel pack. For example, in an open-hole completion, packers are not installed when a gravel pack is utilized because it is not possible to form a complete gravel pack above and below the packer. Without a gravel pack, various problems may be experienced. For instance, if one of the intervals in a formation produces water, the formation may collapse or fail due to increased drag forces and/or dissolution of material holding sand grains together. Also, the water production typically decreases productivity because water is heavier than hydrocarbons and it takes more pressure to move it up and out of the well. That is, the more water produced the less pressure available to move the hydrocarbons, such as oil. In addition, water is corrosive and may cause severe equipment damage if not properly treated. Finally, because the water has to be disposed of properly, the production of water increases treating, handling and disposal costs.
This water production may be further compounded with wells that have a number of different completion intervals with the formation strength varying from interval to interval. Because the evaluation of formation strength is complicated, the ability to predict the timing of the onset of water is limited. In many situations reservoirs are commingled to minimize investment risk and maximize economic benefit. In particular, wells having different intervals and marginal reserves may be commingled to reduce economic risk. One of the risks in these configurations is that gas and/or water breakthrough in any one of the intervals threatens the remaining reserves in the other intervals of the well completion. Thus, the overall system reliability for well completions has great uncertainty for gravel packed wells.
Accordingly, the need exists for method and apparatus that provides zonal isolation within a gravel pack, such as an open-hole completion. Also, the need exists for a well completion apparatus and method that provides alternative flow paths for sand control devices, such as sand screens, and packers to gravel pack different intervals within a well.
Other related material may be found in at least U.S. Pat. No. 5,588,487; U.S. Pat. No. 5,934,376; U.S. Pat. No. 6,227,303; U.S. Pat. No. 6,298,916; U.S. Pat. No. 6,464,261; U.S. Pat. No. 6,516,882; U.S. Pat. No. 6,588,506; U.S. Pat. No. 6,749,023; U.S. Pat. No. 6,752,207; U.S. Pat. No. 6,789,624; U.S. Pat. No. 6,814,239; U.S. Pat. No. 6,817,410; International Application Publication No. WO 2004/094769; U.S. Patent Application Publication No. 2004/0003922; U.S. Patent Application Publication No. 2005/0284643; U.S. Patent Application Publication No. 2005/0205269; and “Alternate Path Completions: A Critical Review and Lessons Learned From Case Histories With Recommended Practices for Deepwater Applications,” G. Hurst, et al. SPE Paper No. 86532-MS.